Sciencemadness Discussion Board

How hydrodistillation works

khourygeo78 - 2-11-2016 at 10:18

So, I tried to get essential oils by performing hydrodistillation as some here suggested before. I tried imitating other experiments done on the internet, by drowning herb in water and distilling to get water and essential oil floating, but this didnt succeed.
What I got was a whitish water that greatly has a biting smell (I distilled thyme). I was wondering if the white water contains the essential oil supposedly mixed with it, but I'm not sure how to separate the oil.
I remember someone who, after hydrodistillation would only obtain plain clear water, but by exposing to the sun for over a month, a layer of oil separates at the top.
Any idea about how I could obtain the essential oil in this way ? (hydrodistillation)
Thanks

Chemetix - 2-11-2016 at 15:04

Sounds like you did get something but not a lot. Some oils separate cleanly from the water others less so and thymol and carvacrol have a hydrophilic nature about them so I'm not surprised you found separation from water disappointing. Due to the phenol structure no doubt. A similar phenomena happens with anise oils for making ouzo, the oils make a milky opalescence in small quantity when added to water and need quite significant amounts before you will see oil. Steam distilling something like cloves will give a fairly clean amount of visible oils. Or just add a few drops of the pure essential oil into a flask and distil that for practice, see how much you can retrieve as an exercise.

khourygeo78 - 3-11-2016 at 00:21

Quote: Originally posted by Chemetix  
Sounds like you did get something but not a lot. Some oils separate cleanly from the water others less so and thymol and carvacrol have a hydrophilic nature about them so I'm not surprised you found separation from water disappointing. Due to the phenol structure no doubt. A similar phenomena happens with anise oils for making ouzo, the oils make a milky opalescence in small quantity when added to water and need quite significant amounts before you will see oil. Steam distilling something like cloves will give a fairly clean amount of visible oils. Or just add a few drops of the pure essential oil into a flask and distil that for practice, see how much you can retrieve as an exercise.


So I guess there's no way to separate the essence from the water?

And I tested on other herbs & flowers, pretty much all give white water. I even could separate a volatile oil from flax seeds once using alcohol as solvent, but when I added water expecting to get the oil to float on top, I got a white water instead. I did this with a few other plants too.

And I guess that hydrodistillation isnt the best way. I should look for a better one using volatile solvents to retrieve the oils.

Tsjerk - 3-11-2016 at 02:21

It depends on how volatile your oil is. You could extract the white suspension with a low boiling hydrophobic solvent and evaporate the solvent. This only doesn't work with very volatile extracts as you would lose your product with the solvent evaporation.